Ошибки в роботах: ожидание и реальность

Несколько наиболее простых и забавных ошибок, которые я нашел с помощью анализатора кода PVS-Studio в проекте RT-Thread.

RT-Thread is an open source IoT operating system from China, which has strong scalability: from a tiny kernel running on a tiny core, for example ARM Cortex-M0, or Cortex-M3/4/7, to a rich feature system running on MIPS32, ARM Cortex-A8, ARM Cortex-A9 DualCore etc. github.com/RT-Thread/rt-thread

Предупреждения PVS-Studio:

V560 CWE-571 A part of conditional expression is always true: 0xFFFF0000. peci.c 372
V560 CWE-571 A part of conditional expression is always true: 0x0000FFFF. peci.c 373

#define PECI_M0D0C_HITHR_M      0xFFFF0000  // High Threshold
#define PECI_M0D0C_LOTHR_M      0x0000FFFF  // Low Threshold

void
PECIDomainConfigGet(....)
{
  unsigned long ulTemp;
  ....
  ulTemp = HWREG(ulBase + PECI_O_M0D0C + (ulDomain * 4));
  *pulHigh =
    ((ulTemp && PECI_M0D0C_HITHR_M) >> PECI_M0D0C_HITHR_S);
  *pulLow =
    ((ulTemp && PECI_M0D0C_LOTHR_M) >> PECI_M0D0C_LOTHR_S);
}

Вместо && следовало написать &.

Предупреждение PVS-Studio:
V767 Suspicious access to element of 'w' array by a constant index inside a loop. fsl_dcp.c 946

typedef union _dcp_hash_block
{
    uint32_t w[DCP_HASH_BLOCK_SIZE / 4];
    uint8_t b[DCP_HASH_BLOCK_SIZE];
} dcp_hash_block_t;

typedef struct _dcp_hash_ctx_internal
{
  dcp_hash_block_t blk;
  ....
} dcp_hash_ctx_internal_t;

status_t DCP_HASH_Init(DCP_Type *base, dcp_handle_t *handle,
                       dcp_hash_ctx_t *ctx, dcp_hash_algo_t algo)
{
  ....
  dcp_hash_ctx_internal_t *ctxInternal;
  ....
  for (i = 0; i < sizeof(ctxInternal->blk.w) /
                            sizeof(ctxInternal->blk.w[0]); i++)
  {
     ctxInternal->blk.w[0] = 0u;
  }
  ....
}

Записываем 0 в одну и ту же ячейку массива. Большая часть массива останется неинициализированной. Должно быть написано:
ctxInternal->blk.w[i] = 0u;

Предупреждения PVS-Studio:

V602 CWE-480 Consider inspecting the '(1U < 1)' expression. '<' possibly should be replaced with '<<'. fsl_aipstz.h 69
V602 CWE-480 Consider inspecting the '(1U < 2)' expression. '<' possibly should be replaced with '<<'. fsl_aipstz.h 70
V602 CWE-480 Consider inspecting the '(1U < 2)' expression. '<' possibly should be replaced with '<<'. fsl_aipstz.h 71

typedef enum _aipstz_peripheral_access_control {
  kAIPSTZ_PeripheralAllowUntrustedMaster = 1U,
  kAIPSTZ_PeripheralWriteProtected = (1U < 1),
  kAIPSTZ_PeripheralRequireSupervisor = (1U < 2),
  kAIPSTZ_PeripheralAllowBufferedWrite = (1U < 2)
} aipstz_peripheral_access_control_t;

Вместо < следовало использовать <<. Тогда константы станут равны различным степеням числа 2.

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